In fact they do have a rule... According to The Rulebook (aka wikipedia) the rule states that roughing the passer can be called if "the defender commits intimidating acts toward the passer, such as picking him up and stuffing him into the ground, or wrestling with him." Lawrie clearly should have been penalized 15 yards, and Hester given a first down.

Actually, Lawrie violated another rule too:
Mixed Martial Arts Fouls:
As set out by the Association of Boxing Commissions:[6]
Attacking an opponent on or during the break
But at least he avoided these no-nos:
Holding or grabbing the fence
Holding opponentâ€™s shorts or gloves
Butting with the head
Eye gouging of any kind
Biting or spitting at an opponent
Hair pulling
Fish hooking
Groin attacks of any kind
Intentionally placing a finger into any orifice, or into any cut or laceration of your opponent
Downward pointing of elbow strikes (see Elbow strike)
Small joint manipulation
Strikes to the spine or back of the head (see Rabbit punch)
Heel kicks to the kidney
Throat strikes of any kind, including, without limitation, grabbing the trachea
Clawing, pinching, twisting the flesh or grabbing the clavicle
Kicking the head of a grounded opponent
Kneeing the Head of a grounded opponent
Stomping of a grounded fighter
The use of abusive language in fighting area
Any unsportsmanlike conduct that causes an injury to opponent
Attacking an opponent who is under the care of the referee
Timidity (avoiding contact, or consistent dropping of mouthpiece, or faking an injury)
Interference from a mixed martial artist's seconds
Throwing an opponent out of the ring or caged area
Flagrant disregard of the refereeâ€™s instructions
Spiking an opponent to the canvas on his or her head or neck (see Piledriver)
Attacking an opponent after the bell has sounded the end of the period of unarmed combat

I was really hoping Jordan Walden was gonna shove a 98 mph fastball into the middle of Lawrie's back after that garbage, but then I realized that Jordan Walden can't locate any of his pitches for shit, and gave up on that idea pretty quickly.

That was an incredibly athletic play Lawrie made - notice how he had the body control to drag his right toe across the dish after he competitively tried to knock the ball loose. Legal Baseball Play.
John Hester's a touch sombitch in his own right - and he made an equally athletic play to catch the ball, take a hit, and yet still block the plate with his right foot as his momentum took him away - and then get what looks to be a tag on the shoulder blade.
I think Hester's last milli-second kick of the leg causing Lawrie to go up and over with his right toe before tapping it on the dish - allowed the tag on the shoulder blade to be in time: OUT.
As an Umpire - we call these BASTARD CALLS ....the play happens and you are a Bastard to one dugout or the other no matter how you call it.